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August 7, 2008 — 研究者报告指出，吃鲔鱼和其他鱼类可以降低无临床症状之梗塞和白质异常的发生率。
在8月5日的神经学(Neurology)期刊中，研究者指出，老年人适度食用鱼类，磁振共振造影(MRI)显示可以降低脑部异常。
第二作者、华盛顿大学的David Siscovick医师在访问中表示，这项研究的差异之一是我们检视多种鱼类，我们也发现，烧烤的鱼类比较好，煎炸的鱼类不好。
研究发现指出，之前的证据认为，富含EPA和DHA的鱼类有重要的临床利益；美国心脏学会建议，人们每周至少吃鱼两次，包括食用鲭鱼、鲱鱼、鲔鱼和鲑鱼等富含omega-3脂肪酸的鱼类。
Siscovick博士向Medscape Neurology & Neurosurgery表示，我们的资料和此建议一致；他鼓励医师和病患讨论食用鱼的种类，他建议，告诉人们多吃鱼但未提供这些细节的谘商，并不会有同样的好处。
目前的研究中，芬兰Kuopio大学的Jyrki Virtanen博士领导的研究人员，检视 3,660名年纪在65岁以上者的资料，这些人属于心血管健康研究这项族群基础研究的研究对象，所有人一开始都接受MRI，五年后，有2,300人左右接受第二次扫描。
神经放射学家以标准单盲方式评估MRI，研究者使用食物频率问卷评估饮食，已知有脑血管疾病者之参与者不纳入析。
【每周吃三次以上的鱼会有好处】
调整多项风险因素之后，研究者发现，相较于每个月吃不到一次鱼者，每周食用鲔鱼和其他鱼类三次以上者，发生一处以上无临床症状梗塞的风险较低(相对风险、0.74; 95% CI, 0.54 – 1.01; P = .06; P 趋势值= .03)。
他们发现，吃鱼也与降低无临床症状的梗塞有关，鱼与较佳的白质等级也有关，但是对于脑病变的标记－脑回和心室等级无关；研究者观察发现，吃炸制鱼类与任何无临床症状的脑部异常无显著关联。
研究者指出本研究的诸多强度，例如是族群基础研究、纳入的样本数大、其他风险因素的扩大标准检视，他们也前溯收集饮食和MRI检查资料。
不过，此研究也有一些限制；他们指出，虽然不同判读者之间对于白质和心室等级的的信赖度不错，但脑回等级的评估在不同判读者之间有比较大的差异；研究者也指出，观察到的关联可能也与食用鱼类以外的不同状况有关，例如较健康的生活型态。他们写道，不过，我们校正了其他风险因素和生活型态习惯。
研究者建议，进行食用鱼类或者鱼油的随机试验，以评估减少无临床症状缺血事件的潜在利益；他们认为，对于容易发生此类事件的年长者，这类研究将是可行且重要的。
研究者宣称没有相关资金上的往来。
Eating Fish May Reduce the Risk for Subclinical Brain Abnormalities
By Allison Gandey
Medscape Medical News
August 7, 2008 — Dietary intake of tuna and other fish appear to lower the prevalence of subclinical infarcts and white-matter abnormalities, report researchers.
In the August 5 issue of Neurology, investigators show that a modest intake of fish among older adults was associated with fewer brain abnormalities on magnetic resonance imaging (MRI).
"One of the differences in this study is that we looked at various types of fish," second author David Siscovick, MD, from the University of Washington, in Seattle, said during an interview. "We also found that broiled and baked fish appeared to be beneficial, while fried fish was not."
The findings add to prior evidence suggesting fish with higher eicosapentaenoic and docosahexaenoic acid content appear to have clinically important health benefits. The American Heart Association advises that people eat fish at least 2 times a week. The recommendation promotes fatty fish such as mackerel, herring, tuna, and salmon — all high in omega-3 fatty acids.
"Our data are consistent with this recommendation," Dr. Siscovick told Medscape Neurology & Neurosurgery. He urges clinicians to discuss with patients the type of fish and how it is prepared. "Telling people to eat more fish without counseling them on these details may not have the same impact," he advised.
In the current study, investigators led by Jyrki Virtanen, PhD, from the University of Kuopio, in Finland, looked at 3660 participants aged 65 years and older. Patients were part of the population-based Cardiovascular Health Study, and all participants underwent MRI at baseline. Five years later, just over 2300 had a second scan.
Neuroradiologists assessed MRIs in a standardized and blinded manner. The researchers used food frequency questionnaires to assess diet, and participants with known cerebrovascular disease were excluded from the analysis.
Consuming Fish 3 or More Times a Week Beneficial
After adjusting for multiple risk factors, the researchers found that the risk of having 1 or more prevalent subclinical infarcts was lower among individuals who consumed tuna and other fish 3 or more times a week compared with those who ate fish less than once a month (relative risk, 0.74; 95% CI, 0.54 – 1.01; P = .06; P for trend = .03).
They found that fish consumption was also associated with trends toward lower incidence of subclinical infarcts. And fish was linked to better white-matter grade, but not with sulcal and ventricular grades — markers of brain atrophy. Investigators observed no significant associations between fried-fish consumption and any subclinical brain abnormalities.
The researchers point to several strengths of their study, such as the population-based recruitment, the large numbers of participants enrolled, and the extensive standardized examinations of other risk factors. They also prospectively collected data on dietary intake and MRI findings.
But the study also had several limitations. They note that although interreader reliabilities of white-matter and ventricular grades are good, estimates of sulcal grade tend to have greater interreader variability. The researchers also point out that the observed associations could be related to other differences related to fish consumption, such as a healthier lifestyle in general. "However," they write, "we adjusted for a variety of other risk factors and lifestyle habits."
The investigators recommend that randomized trials of fish or fish-oil intake be conducted to assess the potential to reduce subclinical ischemic events. Such studies, they suggest, would be feasible and important given the high incidence of such events in older adults.
The researchers have disclosed no relevant financial relationships.
Neurology. 2008;71:439-446.Abstract